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Makotosun

New CT1 project

  • adguy2112
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New CT1 project was created by adguy2112

Hi everyone, just picked up a CT1 and digging into it. No clutch action so I went to see if I could adjust it. Adjustment screw was missing so fashioned my own. The bike was missing the key switch but the seller provided one which I installed. Wires were crispy but I was able to use a multi tester to follow continuity to the rectifier. Coil black was also disconnected but the two wires coming out of the loom seemed to be the correct connection. No spark so removed mag. Points were crusty and some residual oil seems to indicate a leaking crank seal. (We’ll tackle that in due time) cleaned points and checked for loose condenser wires. No spark on kick. My digital meter needs a new battery but analog seems to be operating. Disconnected cap and black wire from coil. Ohms seem okay on secondary but primary is way low. Single wire coils seem hard to find. Any leads anyone? Not sure which universal emgo fits. Would prefer NOS but that may be a dream. I’ll try to check points and condenser resistance once I get digital meter battery today.   Hi everyone, just picked up a CT1 and digging into it. No clutch action so I went to see if I could adjust it. Adjustment screw was missing so fashioned my own. The bike was missing the key switch but the seller provided one which I installed. Wires were crispy but I was able to use a multi tester to follow continuity to the rectifier. Coil black was also disconnected but the two wires coming out of the loom seemed to be the correct connection. No spark so removed mag. Points were crusty and some residual oil seems to indicate a leaking crank seal. (We’ll tackle that in due time) cleaned points and checked for loose condenser wires. No spark on kick. My digital meter needs a new battery but analog seems to be operating. Disconnected cap and black wire from coil. Ohms seem okay on secondary but primary is way low. Single wire coils seem hard to find. Any leads anyone? Not sure which universal emgo fits. Would prefer NOS but that may be a dream. I’ll try to check points and condenser resistance once I get digital meter battery today.  
The following user(s) Liked this Post: MarkT, JayB, Pete-RT1, msavitt, Sneezles61
25 Aug 2021 08:16 #1

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Replied by adguy2112 on topic New CT1 project


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Replied by MarkT on topic New CT1 project

I've used the 24 71532 but you have to make a bracket/mount for it.  Others recommended it and it's my go-to spare.  I've used the same one on points or CDI and nice hot spark.

Yamaha coils are usually pretty good though. Even if readings are off a little they seem to work good.  Might just be dirty points still
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
25 Aug 2021 17:12 #3

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Replied by adguy2112 on topic New CT1 project

Thanks Mark. I rechecked ohms. Secondary didn’t register anything. Primary was super low. Figured to check points again and see how it goes. Placed a piece of thin cardboard between points. Had continuity on both sides so removed the connection to the points. Continuity disappeared. I have continuity from ground to the points wire and, Since the points wire is connected to the condenser there is also continuity at the solder to ground. I’m not great at electrical issues but it seems to me there is a positive wire touching ground (earth) somewhere in the harness. I’ll plan to follow it back from the stator plate and see if I can locate it. Does that sound like the best plan?
25 Aug 2021 23:32 #4

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Replied by MarkT on topic New CT1 project

Make sure key is on if you have stator connected to harness.  Key grounds black (points wire) to kill spark.

With points open there will still be continuity to ground even with stator unplugged. (I would test with stator unplugged and connecting meter to black points wire coming out of stator)  Points closed should give you zero resistance.  Points open should be about 1 to 2 ohms resistance.  Best to use an old fashioned analog meter with an Rx1 scale in my experience. 

Zero resistance on the coil is a problem. Since you said secondary, unscrew plug cap and test again.  Caps go bad more than coils.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
26 Aug 2021 06:28 #5

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Replied by apex on topic New CT1 project

I saw that CT1 on Craiglist I think, was a good price. Akront rear rim is the giveaway.

Original Yamaha parts are robust, most likely dirty points are still your issue, but could be the key switch as well that was not installed when you got it. 

Disconnect the key switch and see if you have spark.

If not, the trigger wire from the mag is black to the ignition coil, and there are two black female leads on the stator harness, one is intended for testing so should be left unplugged (lower one) and the top one with the other wires goes to the black out of the wire harness. Double check those connections.

If OK, then look through the flywheel windows to make sure the points are actually opening when turning the flywheel by hand.

If OK, clean the point faces REALLY good. Even a very small amount of crud or debris is enough to prevent the points grounding when closed. A VERY small amount, I have second guessed myself many times. Most likely this is where your problem lies.
Allrighty Then
26 Aug 2021 07:11 #6

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Replied by adguy2112 on topic New CT1 project

Thanks Apex, really appreciate you taking the time to offer these suggestions. Nice guy up there in Redding. I didn't see his collection but he did send me a pic of his pristine LT3. Gorgeous mini. Didn't ask questions this time...just bought the bike. Seems the project was underway but he gave up. Maybe worse with electrical than I am...or something else (sinister music starts). Still, $1200 was good and I'll eventually get it going.

On points, upped my sanding from 2K to 220 grit for a few secs and wiped clean. closed they appear to be mating perfectly but you never know. I should probably go back with fine grit to finish. They were opening before I removed the mag but I'll recheck once I put it back together. The two black wires coming out of the harness under the tank were tied together with a female that had been cut at the halfway point on the connector. I have both the same way going into a new female pin connector. I'll redo this and use one of the wires. Does it matter which one? I'm not sure which wire would be the "top" one. Perhaps it would have been clearer before someone changed the original configuration I can try to chase them back to see which one connects to the points connector. I'll try disconnecting the switch. All the wires or just certain wires? There is the 6 pin block (one not used) then the white and red wires coming out.

I think I'll build a homemade work stand with a ramp this weekend. Seriously over working at ground level.
26 Aug 2021 09:36 #7

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Replied by MarkT on topic New CT1 project

Pull strips of clean white uncoated business card through points until the paper comes out clean.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
26 Aug 2021 09:42 #8

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Replied by adguy2112 on topic New CT1 project

Thanks also, to you Mark for taking the time. I think the key was on but as my badge says "novice" perhaps I'm living up to that title. Great point. I did bench test the coil secondary at the inside pin to make sure the reading was right but I'll try it again with my analog. My eyes started to go when I turned 41 and progressively have gotten worse so it's just harder to focus on seeing the result on the analog scale. I ordered the Emgo coil so I'll have it just in case and as a back up. Points and condensers are pretty spendy on Partzilla so hopefully, if I need to replace these, some of those on ebay are up to snuff. Looking forward to seeing the blue flame of success so I can see how this beast runs.
26 Aug 2021 10:14 #9

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Replied by Sneezles61 on topic New CT1 project

Yes, a real pain working on the floor... At 6'-2"... getting there is easy... but removing the carcass from the floor... Does gravity weigh more as I age?
  I'm finding its easier to remove the engine... put it on a rolling stand and tinker away... Shining lights where I'm tinkering is much easier.. 
I wonder if those magnifying goggles with a light on them help?
Sneezles61
26 Aug 2021 10:52 #10

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